SINGLE BUBBLE AIR-GUN ARRAY FOR DEEP EXPLORATION

Large tuned air-gun arrays operated in off-shore petroleum exploration are also used for deep penetration marine seismic reflection surveys conducted to define structures in the earth's crust. Because of the attenuation of higher frequencies, the useful upper frequency limit of these records is usually about 50-60 Hz. The aim of this paper is to report on a method of seismic pulse generation that preferentially concentrates the air gun's energy in the low range of the seismic frequency band by centering the output on the first ''bubble pulse'' instead of the initial (primary) pulse. Experimental results show that, due to the increased low-frequency energy content of this ''single bubble'' pulse, air-gun arrays considerably reduced both in size and volume can generate the necessary acoustic energy for deep seismic exploration.